Cutter for well drills



April 21, 1936.

F. SCOTT ET AL CUTTER FOR WELL DRILLS Filed March 9, 1955,

" qsbwfeh L F/ayd L 56027 INVENTORS ATTORNEY Patented A r. 121, 1935 2,038,386

UNITED STATES PATENT oFFlcE CUTTER- roa WELL mums Floyd L. Scott, Houston, Tex and Herman A. Schaefler, Los Angelcs, Calii'., assignors to Hughes Tool Company, Houston, Tex a corpo-u ration of Texas I Application March 9, 1935, Serial No. 10,254

7 Claims. (Cl. 255-71) Our invention relates to well drills and more ticular cutter shown are not directed in a line particularly to hard formation drills which are longitudinally of the axis of the cutter but are intended to drill upon rock and other hard formainclined with the inner end or each tooth intion and employing cutters of v a general conical clined forwardly toward the direction of rotation shape adapted to surround the ends of the shafts of the bit head, said bit rotating in the direction upon which they are mounted. of the arrow in Fig. 2. The teeth 5 are inclined This general type of bit is now old in the art. in the opposite direction, the forward end of the The invention resides in the particular constructeeth being directed rearwardly away from the tion of the cutting surface of the cutters employed. direction of rotation. On the remaining cutter 0 and the position in which they are placed relative the teeth 6 are cut longitudinally of the cutter to each other upon the lower end of the bit. 3 and are directed toward the apex of the cone. An important object of the invention is the pro- Thus these outer rows of teeth 4, 5 and 6 on the vision of cutting teeth upon the outer surface different cutters will engage the bottom of the of the cutters which are formed to cut separate hole, the teeth 4 and 5 cutting an p and diiferent imprints upon the bottom of the DreSSiOn p t r d the Cutter 5 forming 15 hole, no two cutters having teeth which may track a line directly across it, each of them cutting a in the impressions on the bottom of the hole slightly different portion of the bottom, making made by the teeth of the other cones. it impossible for the outer rows of teeth on the It is another object of the invention to provide three cutters to track on the bottom of the hole teeth arranged toward the smaller ends of the as is the usual tendency in bits of this character. 20 cutters to cut effectively upon the bottom of the Adjacent the outer row of teeth on each cutter hole by a combined scraping and chisel action. is an inner row which are numbered 1, a and 9 It is a further object of the invention to mount on the three'separate cutters. The cutter having the cutters in an offset position relative to each the teeth 1 thereon has the crests of the teeth other so that a true rolling action of the conical directed rearwardly from the direction of ro- 5 cutters is prevented thereby giving ascraping as tation; the teeth 8 are directed forwardly in the well as a chisel action to all of the cutting area direction of rotation at their inner ends and the of the cutters. 1 o teeth 9 on the remaining cone are cut radially In the drawing herewith Fig. 1 is a side elevaof the cone. Thus in this second row of teeth tion of a well drill employing the invention. the ma ks l ft by t c st of the teeth up n t 30 Fig. 2 is a bottom plan view showing the cutters Well bottom will form impressions similar to those detached from the head but arranged in operating on the Outer row but the notches p n e W position so that the operation of the cutters may bottom cut by the teeth I and 8 are in the direcbe better understood. tion reverse to those of the outer rows of teeth. It The head upon which the cutters are o nted is to be noted that the two outer rows of teeth 35 is of ordinary construction having an upwardly are separated from each other by a cleft pr notch tapered shank lthereon for attachment to the wh is approximately p t at t e usual drill collar or coupling member. There are teeth as shown in the row 6 in Fig. 2 is, started in this modification three downwardly extending at one point upon the crest of the teeth and is 4 legs2 formed upon the cutter head. Each of these extended around the cone in a Spiral d e o 40 legs has an inwardly flattened face at 3 from sothat when the entirecircumference of the cone which the shafts extend to support the cutters 4. has been cut the groove is of general Spi l fo This supporting structure is old in the art, and a W b Obvious f th d aw need not be shown in detail. Forwardly on the cone from the two outer rows h formation of th tter which forms the of teeth area plurality of rows of teeth ll. These 45 I subject matter of this improvement is shown best rows of teeth have a crest l2 which runs circumin Fig. 2. I have shown three of these cutters ferentially around the cone but in a spiral rather mounted upon their supports in an offset posithan truly circumferential direction. The axis of tionrelative to each other and to the axisof the this spiral tooth with crest I2 is inclined toward '50 drill. In other words, thecentrallongitudinal theaDe 0f the ne. making each row of teeth axis of each cutter is pointed in a direction somewhat saucer-shaped so that they will have tangent to a circle about the central axis. Each the action upon the well bottom of adisc plow, cutter is provided with an outer row of teeth The crests of the spiral cutting edges are notched which are numbered on the three cones by the and at the end of the spiral are forwardly pronumerals 4, 5 and 6. The teeth 4 on the parjecting spear points orteeth l3 formed to cut 55 the center of-the hole and prevent the formation of a core upon the well bottom at that point.

These points 13 are designed so that the three the full centerof made by the preceding or succeeding outer rowsl The inner spiral rows of teeth upon each cutter are moved about the center of the hole with a combined rolling and scraping action which tends to plow the bottom of the hole with the forward cuttmg crest l2 upon each tooth. This effects the cutting of the central portion of the hole in the most eflicient manner. The arrangement of the three cutters is such that they will each cut an independent track upon the bottom of the hole, serving to prevent the tendency vin bits of this character to form notches in the well bottom into which the corresponding, teeth of all of the cutters engage. Tracking is directly avoided and a most eflicient cutting action obtained due to the independent action of each tooth in well bottom.

vWhat we claim as new is:

1. In a well drill, a head, three approximately conical shaped cutters mounted on the forward end of said head to roll upon the bottom of the hole being drilled, each of saidcutters having its longitudinal axes directed to one side of the cen tral axis of the drill, teeth at the bases of said cutters having chisel shaped edges, the .corresponding rows of teeth adjacent the base on each cutter having crests inclined relative to the eut- T ter axis in a direction different from the direction of those on adjacent cutters, and teeth-on each cutter adjacent the apex thereof having cutting edges extending around the cone and their cross sectional axes inclined toward the central axis of said drill. a

2. In a well drill, a head, three approximately conical shaped cutters mounted on the forward end of said head to roll upon the bottom of the hole being drilled, each of said cutters having its longitudinal axes directed to one side of the central axis of the drill, teeth at the bases of said cutters having chisel shaped edges inclined relative to the cutter axis in a'direction differentfrom those on adjacent cutters, and teeth on each cutter adjacent the apex thereof having cutting edges extending spirally around the periphery of the cone with their cross sectional axes inclined toward the center of said hole.

3. In a well drill, a head, three approximately conical shaped cutters mounted on the forward end of said head to roll upon the bottom of the hole being drilled, each of said cutters having its longitudinal axes directed to one side of the central axis' of the drill, teeth at the bases of said cutters having chisel shaped edges, the corresponding rows of teeth adjacent the base on each cutter having crests extending approximately longitudinally of the conical surface and inclined relative to its axis in a direction difi'erent from those on adjacent cutters, and teeth on each engaging the cutter adjacent the apex thereof having their axes inclined toward the center of the hole.

4. In a well drill, a head, a plurality of approximately conical shaped cutters mounted at the forward end of said. head to roll upon the bottom of the hole being drilled, two rows of teeth adjacent the base on two of said cutters extending approximately longitudinally of the conical surface but the crest of the teeth in each of said two rows on each of said two cutters being formed to make a cut on the bottom of the hole inclined in a different direction with respect to radius of the hole from that of the other row on the same or on adjacent cutters so that the corresponding teeth on one cutter will not track in the cuts formed by adjacent cutters, and teeth on each cutter toward the apex thereof having their crests extending in an approximately circumferential direction about the surface of the cutter.

5. In a well drill, a head, a plurality of approximately conical shaped cutters mounted at the-forward end of said head to roll upon the bottom of the hole being drilled, said cutters be ing positioned with their longitudinal axes ofiset relative to the central axis of the drill to obtain a partial scraping action, a spirally inclined outer row of teeth at the base of each cutter having their crests of chisel shape and formedon the cutter to' cut tracks on the well bottom directed inwardly from the wall of the well at different angles, and a spiral'row of teeth between said outer row of teeth and the apex of each cutter, the crests of which extend approximately circumferentially of the cone and their axes inclined toward the central axis of said head to engage the well bottom with a plowing action.

6. In a well drill, a head, a plurality of approximately conical shaped cutters mounted at the forward end of said head to roll upon thebottom of thehole being drilled, said cutters being positioned with their longitudinal axes offset relative to the central axis of the drill to obtain a partial scraping action, a spirally inclined outer row of teeth at the base of each cutter having their crests of chisel shape and formed on the cutter to cut tracks on the well bottom directed inwardly from the wall of the well at various angles so that the said tracks cannot coincide, and a row of teeth extending spirally about each cutter from said outer row to the apex and having cutting edges thereon approximately circumferentially of the cutters.

7. In a well drill, a head, a plurality of approximately conical shaped cutters mounted on the forward end of said head to roll upon the bottom of the hole being drilled, two outer rows of chisel-shaped teeth extending circumferentially about the base of each cutter, the crests of the teeth in each row on each cutter extending in a different direction relative to the longitudinal axis of the cutter from that of the crests of teeth on the adjacentrow, the direction of inclination of the said crests of teeth on each cut- -ter being varied, so that the teeth of each row on each cutter will cut a separate impression upon the well bottom. FLOYD L. SCOTT. HERMAN A. SCHAEFFER. 

